States of Matter & Solid State Chemistry

Sublimation is the transition of a substance from the solid phase to the gas phase without passing through an intermediate liquid phase.

Triple Point is the temperature and pressure at which solid, liquid, and vapour phases of a particular substance coexist in equilibrium. A specific case of phase equilibrium. e.g.The triple point for water is at 0.01^o Celsius at 4.56 mm Hg.

Gases do not posses any definite shape or volume. They completely fill all the space available to them. The tendency of a gas to fill the available volume within a container is the result of the freedom that gas particles have to move everywhere in the available space. As a result the molecules of gas are in a continuous motion and are associated with high velocity and therefore high kinetic energy.

In molecular crystals, the constituent particles are molecules. These molecules are held together by weak forces known as Van der Waal's forces. Common examples are dry ice, wax, iodine, sulphur, etc.

In metallic crystals the constituent particles are positive kernels i.e., nuclei where inner electrons are dispersed in a sea of mobile valence electrons. The forces present between the constituents are metallic bonds.

The ionic crystals consist of positively and negatively charged ions arranged in a regular fashion throughout the crystal. They form a network of positive and negative ions in three dimension in such a way that cations and anions occupy alternate sites. These are held together by strong electrostatic forces.Common examples of ionic crystals are, salts like NaCl, KNO₃, LiF etc. 

The conversion of a liquid into its vapour at its boiling point is called as vaporization. So ,when a liquid converts into its vapour at its boiling point it is said to be ,vapourised. During the process of evaporation, cooling always occurs. This is because during evaporation the molecules of higher kinetic energy escape. The slow moving molecules are left behind.

When some of the lattice sites are vacant the solid is said to have vacancy imperfection. It decreases density of substance and can be generated by heating the solids.

Liquid will always take up the same amount of space and have the same number of molecules in it. Liquids, however, do not have a definite shape. Liquids take on the shape of the containers they are in. Paint and juice are just two examples of liquids.

Volume has no effect on rate of evaporation

Robert Boyle proposed this law , giving the relationship between pressure and volume of given mass of a gas at constant temperature. This law states that volume (V) of a given mass of gas is inversely proportional to the pressure (P) at constant temperature. Mathematically it can be expressed as, or PV = k = constant.  At a given temperature, when the pressure of the gas is changed from P1 to P2 the relation becomes P1 V1 = P2 V2 = constant where, V2 is the new volume of the gas. The product of volume and pressure for a given mass of a gas at constant temperature is constant.

It is a non stochiometric point imperfection .There are many solids which are difficult to prepare in the stoichiometric composition and contain less amount of metal as compared to stoichiometric proportion.

Gases are formed when the energy in the system exceeds all of the attractive forces between molecules. Thus gas molecules have little interaction with each other beyond occasionally bumping into one another. In the gas state, molecules move quickly and are free to move in any direction, spreading out long distances. As the temperature of the gas increases, the amount of movement of individual molecules increases. Gases expand to fill their containers and have low density.

Each state of matter has distinctive properties that can be used to identify it. Each of these states of matter is also known as a phase. Things can move from one phase to another phase when special forces are present. For example, temperature can cause matter to change phases. Water is a liquid but if temperatures drop low enough, water can turn to ice, which is a solid.

Ideal gas does not obey Van Der Wall's equation. It is obeyed by real gases. A real gas, does not obey the general gas equation and other gas laws at all conditions of temperature and pressure.

Condensation can be defined as the change in the state of matter from the gaseous phase to the liquid phase. e.g.conversion of water vapours into water.

In the solid phase the molecules are closely bound to one another by molecular forces. A solid holds its shape and the volume of a solid is fixed by the shape of the solid. It never takes the shape of the container.

 It may be defined as the temperature above which a gas cannot be liquefied by application of pressure. A gas will remain as gas above critical temperature and in order to liquefy it by compression, it has to be cooled to its critical temperature. Critical temperature is denoted by T_c.

In order to explain the observed behaviour of gases, a model was proposed based on the molecular and kinetic concept of gas molecules. This model takes into account the particulate nature of matter and the constant movement of particles.